This multinational, multicenter, randomized, double-masked controlled clinical trial has been designed to evaluate the efficacy of inhaled nitric oxide (INO) in the treatment of term and near-term infants with hypoxic respiratory failure. The proposed trial will compare INO therapy to a control group that receives either oxygen or no flow as a control. Infants greater than or equal to 34 weeks gestation with the diagnoses of respiratory distress syndrome, meconium aspiration, sepsis/pneumonia, idiopathic persistent pulmonary hypertension of the newborn, suspected pulmonary hypoplasia, and congenital diaphragmatic hernia will be eligible for the trial. The primary outcome will examine INO's ability to reduce the need for extracorporeal membrane oxygenation (ECMO) or death. The trial is being conducted jointly by the Canadian Inhaled Nitric Oxide Study Group (CINOS) and the NICHD Neonatal Intensive Care Units Network. Infants are followed to death or discharge to home with a neurodevelopmental assessment obtained at 18 - 24 months corrected age on the surviving infants.